2002/09/30 by S. Carlip, Steven Carlip · 1 citation
Physics and Astronomy · #Black Holes and Theoretical Physics #Black hole (networking) #Black hole thermodynamics #Classical mechanics #Cosmology and Gravitation Theories #Entropy (arrow of time) #Membrane paradigm #Micro black hole #Noncommutative and Quantum Gravity Theories #Physics #Quantum #Quantum gravity #Quantum mechanics #Statistical physics #Theoretical physics #astro-ph #gr-qc #hep-th
paper · pdf · doi:10.1103/physrevd.67.023507
published as Phys.Rev.D67:023507,2003 · 10 pages, LaTeX; v4: substantially rewritten to emphasize assumptions and ``loopholes,'' but basic conclusions unchanged; to appear in Phys. Rev. D
arxiv created 2002/11/14 · openalex publication_date 2003/01/16 · arxiv updated 2010/04/28 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Tentative observations and theoretical considerations have recently led to renewed interest in models of fundamental physics in which certain ``constants'' vary in time. Assuming fixed black hole mass and the standard form of the Bekenstein-Hawking entropy, Davies, Davis and Lineweaver have argued that the laws of black hole thermodynamics disfavor models in which the fundamental electric charge e changes. I show that with these assumptions, similar considerations severely constrain ``varying speed of light'' models, unless we are prepared to abandon cherished assumptions about quantum gravity. Relaxation of these assumptions permits sensible theories of quantum gravity with ``varying constants,'' but also eliminates the thermodynamic constraints, though the black hole mass spectrum may still provide some restrictions on the range of allowable models.